With advantages of low voltage, high luminous efficiency, low energy consumption, long service life and no pollution, white light-emitting diode (white LED) has been successfully used in the semiconductor lighting field and the flat panel display field. Current white LED is mainly realized in the following two ways: way 1, a white LED is formed by combining LED chips of thee primary colors (red, blue, green); way 2, fluorescent substances are excited by LED chips to emit lights, and the lights emitted from the fluorescent substances are mixed together with the lights from the LED chips, then form white light, that is, a blue LED chip is cooperated with a fluorescent substance emitting yellow light, or a blue LED chip is cooperated with a fluorescent substance emitting green light and a fluorescent substance emitting red light, or an ultraviolet or a purple LED chip is used to excite a red fluorescent substance, a green fluorescent substance and a blue fluorescent substance. In these realization ways, the forming of a white LED through the cooperation of a blue LED chip with a yellow fluorescent substance Y3Al5O12:Ce is simple, practical and relatively cheap and therefore becomes the mainstream. However, the spectrum of the white light formed in this way is relatively monotonous, mainly concentrated in the yellow area, which leads to the relatively low color rendering property in the white LED preparation. The red color component absent in the spectrum of such a white LED can be compensated by adding an orange-red fluorescent substance during the package process, thereby promoting the color rendering capability of the white LED product.
Nitride/oxynitride fluorescent substance has gained wide attention since its advent. The anion group of such fluorescent substance contains N3− which carries high negative charge, the excitation spectrum of such fluorescent substance moves towards the direction of a long wave (near-ultraviolet light, visible light) under the expansion effect of electronic cloud so that such fluorescent substance emits light under the excitation of blue light and ultraviolet light the wavelength of which is within a range of 200-500 nm, and the dominant wavelength of the emitted light is distributed in a relatively wide range of 600-720 nm. Thus, such fluorescent substance has characteristics of excellent color rendering performance, high luminous efficiency, high safety, no toxicity and environmental friendliness, moreover, as the substrate of such fluorescent substance has a tight network structure, the physical and the chemical properties of such fluorescent substance are stable (e.g. the fluorescent substances disclosed in EP1104799A1, WO2005/052087, CN100340631C, CN101090953A). In silicon-based nitride red fluorescent substance (patent No. CN1918262B), the luminous intensity of a fluorescent substance can be effectively improved through the adjustment and control of Sr on CaAlSiN3:Eu red fluorescent substance. The oxynitride orange-red fluorescent substance provided herein enables fluorescent substance to be regulated and controlled in a wider range, extending the photochromic range of fluorescent substance to an orange area.